Automatic backup failed - Error 7/12/2011 5:20:10 PM The certificate has expired.

Hi, previous backups went ok. This time I received the following email notification.
1 Information 7/12/2011 5:20:05 PM Operation Online Backup started.
2 Error 7/12/2011 5:20:10 PM The certificate has expired.
4 Error 7/12/2011 5:20:10 PM Operation has completed with errors.

I have been using the service since 6 June 2011 without a problem.

Can anyone help.

Thanks
Vic

Edit - I seem to have resolved the problem.
Thanks